Vacuum tube electrode



Oct. 12, 1937. E. P. LOPPACKER VA CUUM TUBE ELECTRODE Filed Nov. 14,1934 INVENTOR Patented Oct. 12, 1937 E i-Si PATENT oFFieE VACUUM TUBEELECTRODE Everett PsLoppacker, Bloomfield, N. J. Application November14, 1934, Serial No. 752,929

2 Claims.

first stamped into cup shape from a flat sheet .and theparts of the cupare then appropriately formedto yield the structure desired for theparticular tube. is v Another object is to reinforce the open end of theelectrode by strengthening means, such as a flange or bead, to increaseits resistance to distortion.

Among other objects of the invention are the production of an electrodehaving increased wall area, and having great strength and rigidity, andalso being relatively free from microphonic noises. While preferredforms of the invention are disclosed herein for purposes ofillustration, various changes may be made in the structure withoutdeparting from the spirit of the invention as hereinafter set forth andclaimed.

In the drawing: Fig. 1 is a side elevation of a plate element embodyingthe invention. V

Fig. 2 is a section on line 2-2 of Fig. 1. Fig. 3'is a fragmentaryvertical section. Fig. 4 is a fragmentary horizontal section.

Fig. 5 is a fragmentary plan. view showing in 7 detail the perforations.V

Fig. 6 is a perspective view of a modified shape of electrode. Fig. '7is afr'agmentary side elevation showing a modified top construction. V i

Fig. 8 is a fragmentary section showing a furthermodification.

Referring to the drawing more particularly,

the electrode element illustrated in Fig. 1 is a 3 and '4. Parts of theside wall are leftimperforate, shown at l3, and are indented so thatsupport'wires may be conveniently, attached to these parts, as by spotwelding. 55 A one-piece homogeneous element formed in the mannerdescribed avoids the necessity for a joint connecting the top to theside wall, as well as the necessity for a vertical joint in the sidewall, and has the following advantages:

1.-Accuracy of manufacture V V By stamping the cup from a single sheetof metal the exact dimensions and alinement of the parts can becontrolled within more narrow limits than where the electrode isassembled from sev- 1Q eral separate pieces.

' 2.- -Strength I Theone-piece electrode has greater strength andrigidity than an assembled electrode. 15

3.-No Zooscness possible An electrode assembled from separate pieces oftin has slight looseness between parts that is present from thebeginning due to defective as- 20 sernbly, or which develops in use dueto the expansion and contraction under repeated heatings and coolings,especially where the tube is subjected to continual vibration as in anautomobile radio.

No such looseness can be present in the one-piece 5 electrode of thisinvention.

Where a rolled tinners seam is used to "join separate parts, the rollingcauses local stresses in 30 the metal, and these stresses causedistortion of the electrode when it is heated in the bombardment processand in use. 7

5.Aooids microphonic noises For the reasons pointed out above theonepiece electrode is free from many of the causes of microphonic noisesin tubes, these noises causing.

the rejection of a high percentage of tubes during manufacture as wellas frequent cases of dissatis- 40 faction in use. i 1 7 In order tofurther stiffen the open end of the electrode it may be formed with afiangeilii, and if 7 still greater rigidity is desired a bead iilmayalso be used, oreitherfbead or flange may berused alone. Thisreinforcing of the open end of the electrode cooperates withthe'one-piece construction to form a strong electrode that will hold itstrue cylindrical form under repeated heatings.

Where the protrusions i2 are'used the inclosed surface area is greaterthan where wire gauze or flat perforated metal is used.

Another way of increasing the surface area is shownin Fig. 8 where theperforated side wall isformed with corrugations I6, the ridges of '55which run horizontally along the side walls of the electrode.

The advantages of increased wall area are that the tube runs cooler,gives less back emission and gives a greater area for the electronicmovement.

The present invention may be applied to electrodes of various shapes,one of rectangular form being illustrated in Fig. 6, and the top may beformed to suit the requirements of the tube, a partly conical top beingshown at I! in Fig. '7

The electrode of this invention may be used either as a plate or as agrid, and due to its rigid one-piece construction, it will maintain thecharacteristics for which it is designed under all temperatures andconditions of use.

I claim:

1. An electrode for a vacuum tube comprising,

a top, a side wall connected with the top, most of the area of the sidewall being formed with perforations, the continuity of perforations insaid wall being interrupted to provide vertically extending imperforateparts of the side wall for the attachment of support wires.

2. An electrode for a vacuum tube comprising a top formed with anaperture, and a, cylindrical wall having an open end and formedhomogeneoils with the top, the top and side wall forming a single piecefree from joints, most of the area of the side wallbeing formed withperforations, vertically extending parts of the side wall being bentinwardly and left imperforate for the attachment of support wires, theside wall being bent into a reinforcing part extending circumferentiallyaround the side wall adjacent the open end.

E. P. LOPPACKER.

